The present disclosure relates to a liquid crystal display element performing a display by a VA mode, and a liquid crystal display device including the same.
In recent years, a liquid crystal display (LCD) has been widely employed as a display monitor of a liquid crystal television, a notebook personal computer, a car navigation system and the like. The liquid crystal display is classified into various display modes (methods) according to a molecular alignment between a panel and a substrate, and, for example, a TN (twisted nematic) mode in which a liquid crystal molecule is twisted and oriented in the state where a voltage is not applied thereto is well known. The TN mode has such properties that the liquid crystal molecule has a positive dielectric anisotropy, that is, a dielectric constant of the molecule is larger in a long axis direction compared with a short axis direction, and the TN mode has a structure in which a liquid crystal molecule is aligned in a vertical direction to a substrate surface, while sequentially rotating an orientation direction of the liquid crystal molecule within a plane parallel to the substrate surface.
Meanwhile, a VA (vertical alignment) mode in which the liquid crystal molecule is vertically oriented to the substrate surface in the state where the voltage is not applied thereto has increasingly attracted attention. The VA mode of the vertical alignment type has such properties that the liquid crystal molecule has a negative dielectric anisotropy, that is, the dielectric constant of the molecule is smaller in the long axis direction compared with the short axis direction, and it is possible to realize a wider viewing angle compared with the TN mode.
The liquid crystal display of the VA mode has such a structure that when the voltage is applied, the liquid crystal molecule vertically oriented to the substrate responds to the voltage by tilting (rising) in the parallel direction to the substrate due to the negative dielectric constant, and light is allowed to transmit. However, the tilt direction of the liquid crystal molecule vertically oriented to the substrate is arbitrary, and the orientation of the liquid crystal molecule is thus disordered by voltage application. This becomes a factor of deterioration in response characteristics to the voltage.
Thus, as a control means of the tilt direction of the liquid crystal molecule responding to the voltage, there has been disclosed a technique that a polymer having a predetermined structure on an opposing face side of the substrate is formed, and the liquid crystal molecule is oriented to tilt in a specific direction from the vertical direction to the substrate (providing a so-called pre-tilt angle) (for example, refer to Japanese Unexamined Patent Publication No. 2003-177408). With such a structure, it is possible to previously fix the tilt direction of the liquid crystal molecule when the voltage is applied, and it is possible to improve the response characteristics to the voltage.